Identification of novel catechin receptor that mediates blood vessel protective effect and vasodilatation, and it's application for functional food

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From preliminary investigation, we found a vasodilatation effect of (+)-catechin on the endothrial cells. The effect was observed within 30 minutes after (+)-catechin treatment in vivo, but not (-)-epigallocatechin gallate, we hypothesized that the existence of novel (+)-catechin specific receptor and that the effect was mediated through the receptor signaling thereby produced NO. In order to identify putative (+)-catechin receptor, we used a differential proteomics approach in the brain of (+)-catechin injected mice. Male, 8-week-old ICR mice were injected 100 mg/ml (+)-catechin intravenously. After 3h injection, the brain was excised and homogenized to extract proteins. The brain extracts were subjected to 2-D PAGE, and then the 2-D gels were silver stained. The spots with a pI of 〜8.1 and a molecular mass of 〜60 kDa and a pI of 〜8.3 and a molecular mass of 〜17 kDa were markedly increased in (+)-catechin injected mouse brain extract compared with vehicle injected control. While the spot with a pI of 〜5.7 and a molecular mass of 22 kDa was decreased. These changes in spots are suspected to be brought about by the post-translational modification such as protein phosphorylation or protein degradation of the putative receptor itself or its downstream signaling molecules. Next, we will try to isolate these protein spots and analyze the amino acid sequences using peptide mass fingerprinting.